Microphone boom



Sept. 13, 1938. A. G. WRIGHT MICROPHONE BOOM Filed Oct. 2, 1936 2Sheets-Sheet 1 G .Y R M O MPO E Vfl M m P 8- A. G. WRIGHT 2,129,898

MICROPHONE BOOM Filed Oct. 2, 1936 2 Sheets-Sheet 2 II I I 0,2

my 1 lp mm '14 Fig. 6

V INVENTOR 37 BY ArtZur G. Wright Fig. 8.

Patented Sept. 13, 1938 UNITED STATES PATENT. OFFICE MICROPHONE BOOMration, Los New York Angeles, Cali!., a corporation of ApplicationOctober 2, 1936, Serial No. 103,715

9 Claims.

This invention relates to extensible microphone booms and deals with a,liquid operated boom.

The boom to be hereinafter described has been developed to meet therequirements of motion picture studio needs, but it will become evidentas the description proceeds that it may find usefulness in other fields,such as broadcasting stations, or any other occasion where an extensibleboom may be needed.

The principal object of this invention is to provide an extensible boomwherein the means for extending the boom comprises a liquid medium.

Another object is toreduce the noise common to the operation of theordinary boom.

Still another object is to combine the counterbalancing weight necessaryin booms of this nature with the means for actuating the liquid inextending the boom.

A further object is to provide an extensible boom wherein the bulk ofthe external equipment common to the ordinary boom is either eliminatedor concealed. In this respect, it is common knowledge that the ordinaryboom comprises cables, pulleys, counter-balancing weights,

5 etc., as external equipment. In my invention, I

eliminate the bulk of these and operate the extensible part of the boomby means of a noncompressible fluid, thus providing a positive actionand avoiding lost motion due to cable slack.

A still further object is to provide an extensible boom characterized byworkmanlike appearance, lightness, durability, and one wherein the costof maintenance will be extremely low.

Other objects and advantages will appear as 5 the description proceedsin conjunction with the drawings in which:

Figure l is aside elevation of my boom complete, showing it partlyextended with the supporting stand broken away. I v 40 Figure 2 is alongitudinal section slightly enlarged of the working parts of the boom.

Figure 3 is a cross section taken on line l3 of Flgure 2. v w

v Figure 4 is a cross section taken on line 4-4 45 of Figure 2.

Figure 5 is a cross section taken on line 5-5 of Figure 2.

Figure 6 is an enlarged section of the piston, showing the manner inwhich the piston isat- 50 tached to the operating mechanism and thecounter-balancing weight.

Figure 'l is an enlarged section of the piston'on the extensible part ofthe boom, showing the manner in which the piston is attached to the g5extensible rod.

Figure 8 shows a part of the rack with the connection to the pistongland.

Figure 9 is a longitudinal section slightly enlarged, showing the outerend of the boom and is a continuation of Figure 2. 5

Referring to the drawings and particularly to Figure 1, it will be seenthat my-boom consists, in general, of a stationary cylinder or barrel,generally designated A. Slidably mounted in the barrel A is a rod memberB, and in the outer end 10 of this rod I mount another rod C, which isadapted to be telescoped within the rod B. The microphone D is attachedto the end of the rod C by the conventional hanger E. At the rear end ofthe tubular member A and, as illustrated, 15 directly beneath thismember, I mount another cylinder or tubular member F. The members A andF contain the liquid and the pistons to be later described. The membersA and F are connected at the rear end by a suitable casting G, 20 whichwill be described in conjunction with the operation of the boom. Theother end of the member F is held by a supporting box H. Extendingforward of the box H is a smaller tubular member J, fixed at the forwardend by a sup- 26 porting spacer K. The box H is adapted to be supportedon a stand L, which may take any form, and is arranged to swing in avertical plane indicated by the dotted lines M and N.

In Figures 2 to 5 the construction and arrange- 30 ment of parts isshown. Referring to Figure 2, which is'an enlarged longitudinal sectionof the barrel arrangements with the pistons and moving parts, it will beobserved that the barrel A passes through and is supported in the box Hand contains an inner sleeve II, which may be of thin,

light material. The double sleeve arrangement provides a more rigid anda more durable construction. It is to bev understood that the innersleeve H extends the full length of the barrel A 40 and is spacedtherefrom at one end by a casting l2. The casting l2 also 'carriesthebarrel A and the barrel F, which are mounted therein in any suitablemanner. The other end of the sleeve I I is spaced from thebarrel A inany suitable manner, not shown. For this purpose a leather ring orscrews extending through the'barrel A may be used. Within the sleeve II, the rod B -is slidably mounted and is attached to a sliding supportI3 and a piston H in a manner to allow a floating action between the rodand the piston. This construction is best shown in Figure '1' and willbe described later. The rod Bis shown as square for purposes of rigidityand alsoto prevent r'ota-' tion of the rod during extension. In-Figure'1',

I have shown rollers l and I6 mounted on the barrel A. These rollersextend through the barrel and the inner sleeve II and are arranged toengage the upper and lower edges respectively of 5 the square rod B. Asthe rod is extended, the rollers not only prevent turning of the rod,but also act as hearing points .for the rod to prevent undue bending. Onthe outer end of the rod B, I mount a telescoping rod C, which isadapted to be extended by hand and on the outer end of the rod C Isuspend a microphone D, mentioned before, by means of the conventionalhanger E.

The foregoing description deals with the extensible part of the boom.The hydraulic means for extending As before stated, the barrel F ismounted directly beneath the barrel A, although it could be mountedabove or to one side if more convenient, and is interconnected with thebarrel A by means of a passage I! in the casting G. A piston I8 isslidably mounted in the barrel F and is connected on one side to asliding weight I! and to a rack bar on the other side. The barrels A andF are filled with a liquid between the pistons i4 and I8, thus forming aliquid link between the two pistons which works through theinterconnecting passage II. It is clear that the liquid connecting thetwo pistons being incompressible, and likewise non-expansible, will forma flexible connection between the two pistons that will operate to workthe piston H in either direction. In other words, when the piston i8applies pressure to the liquid, the piston II will normally move inresponse to the pressure and when the 5 piston i8 moves in the oppositedirection to withdraw the liquid the piston will follow the withdrawalof the liquid, due to atmospheric pressure. It will be noted that thebarrel F being constderably larger in diameter than the barrel A, thepiston I! will move farther than the movement of the piston I8 and that"due to the arrangement of the two barrels the movement of the piston i4is counter to the movement of the piston Ill. The purpose of this is tomove the weight opposite to the movementof the rod B, and thereby effecta counter-balancing action. For purposes of illustration anddescription, I have shown an auxiliary weight I9 attachedto the piston,but it is obvious that the piston l8, being of a large diameter, may bemade of sufllcient length to act as a counterbalancing weight itself, ifdesired. An enlarged detail of this construction is shown in Figure 6.The rack bar 20 extends through the box H and is carried in the tubularmember J. The means for working the rack bar backward and forward willbe disclosed later in conjunction with Figure 5. The pistons l4 and I!are connected by fluid, shown by the broken line portion in the barrelsA and F. Referring the pistons l4 and It will be given. I In theseviews, I have shown enlarged longitudinal sections of the pistons. Thepiston i8 comprises a hub 2| having an intermediate flange 22. .Two cupleathers 23 and 24, placed back to back, are mounted on the hub andbearagainst opposite sides of the. flange. The cup leathers are held inplace by plates 25 and 26, respectively, which in turn are held by nuts21 and 20, respectively,

screw threadedly mounted on the ends of the .hub 2|. The hub is bored toreceive a rod 29 that is pinned inthe hub by a pin 30. In order toprovide a floating connection between the rod 28 and the weight I9. Ipass the rod completely through the weight before attaching it to the.

the boom will now be described.

now to Figures 6 and '7, a detailed description of' weight. It will benoted that the rod does not touch the bushing Ii, which is in the centerof the weight. In Figure 2 it will be seen that the bushing ll extendsbeyond the end of the weight and that the rod 2! is attached to thisextended end by means of a pin 32, thus allowingthe piston a floatingmovement with respect to the weight. The weight I! is equipped withrunners 33, which are circumferentially spaced and may be of anysuitable material conducive to easy sliding and silent operation.Instead of making the weight separate from the piston, it may beincorporated as a part of the piston, if desirable. 0n the forward sideof the piston, the hub 2| extends into a shaft 34, which is bifurcatedat the end to receive the rack bar 2|. A sliding connection is usedbetween the shaft ll and the rack bar 20, that is, there is a floatingaction between these two members. This is accomplished by making thebifurcation in the shaft larger than the tongue 35 on the rack. A pin 2is used to connect the rack bar to the shaft and in order to obtain afull floating action, the pin is fixed to the tongue 35 and works in .atransverse slot 31 in the shaft 34. A piston of this nature will havefree action against the wall of the cylinder and will not be forced toaccommodate itself to transverse movement either of the weight or therack bar. In connecting the piston M to the rod B, I follow the samegeneral idea, but not the same structure. This structure is shown inFigure '7. Here it can be seen that the piston itself consists of twocup leathers 30 and 22, mounted back to back against a flange 40 on ahub H. The cup leathers are held in place by plates 42 and 43respectively, which in turn are held on the hub by screw threadedmembers 44 and II, mounted on the ends of the hub 4|. The hub ll isbored as at 46, and counterbored as at I. A rod 48 extends through thebore 40 and is arranged to not touch any part of the hub II. On theouter end of the rod I mount a screw ll having a flat head. The head ofthe screw is adapted to flt in the counterbore 41 without touching thesides of the bore, but is arranged to engage the shoulder between thebore and the counterbore. With this arrangement, the pistonvll isloosely mounted on the rod 42. In con- Junction with the cup leatherarrangement, I provide means for carrying the end of the rod B so thatits weight will not come on the piston. For this purpose, I provide ahub 50 attached to the shaft 48 by a pin I. The hub $0 carries a flange52 against which there is fastened a fibrous member 53 adapted to engagethe wall of the inner sleeve II. The shaft II also extends through ablock Bl, which is adapted to fit into the end of the square rod B andboth the block and the shaft are attached to the rod B by a pin 55. Thestructure Just described will provide a full floating action of thepiston II with respect to the rod B.

The actuating mechanism and the means for mounting the boom upon asupport are shown in Figures 2 and 3. In'Flgure 3, I have shown a crosssection of the box K. As before stated, the outer barrel A is mounted inthe top of the box H and contains the inner sleeve II and the square rodB. Mounted on the barrel A are two upright standards with a bar 51nmning between them for a handle for controlling the altitude of theboom or' for swinging. the, boom on its support. The box H also supportsone end of the barrel 1", which is left open to. the box. 0n the rearside of the box I form a hub 5!. Inside the bushing, I provide a'shaft00 which is pressed into Below the'hub I8, and a little to one sidethereof, I form another hub 6|, into which a short shaft 82 is pressedand held stationary. .The

box extends around and down into a flange I.

On the front side of the box, I mount a door 64 and on the door I formanother'hub I! which may be provided with a bushing. u. ii desirable.The door may be held in place by screws 81 or in any other suitable way.In the bushing 68 I mount another short shaft 00 and on the inner end ofthe shaft'I fix a pinion gear S9. The

pinion gear is arranged to mesh with the rack bar 20 previouslymentioned. On the outer end oi the shaft 08 I attach a crank 10 forturning the gear 69.- In order to provide good structure, the inner endof the shaft 68 is turned down and extends into the shaft as shown indotted lines 6|. From the foregoing description,

it is evident that the door 54 may be removed and the pinion gear 69withdrawn with the door, thus giving access into the box H and into' theend of the barrel F. Due to the fact that the rack bar 20 is made aslight as possible, I recommend that a roller H be positioned-beneath thebar to prevent bending. The hub GI and the shaft 62 are for thispurpose. In Figure 2. it can beseen that the shaft 62 carries an arm 12pivotally mounted thereon. ,The roller H is rotatably mounted on the endof this arm.v Means is also provided for regulating the pressure of hisroller against the rack bar 20, and as shown comprises a screw 13extending up through the bottom 01' the box H, with a set nut "forholding the screw once it is adjusted. From the foregoing it is obviousthat the rotation of the crank 10 will move the piston i8 and the weightl9 backward or forward inthe barrel F. The forward end of the rackbarin'its' travel is guided in a groove '35 formed in a runner 16 of anysuitable material in the member J, (see Figure 5). The box H may also beformed with an oil sump '3'? having an outlet i8 therein. The wholeassembly hereinbefore described is mounted on the support L. Themounting for this purpose is best shown in Figures 2 and 3. Thesupport Lmay be any form of boom support, such as a tripod or a standard of anydescription and carries onthe upper end an upwardly extending arm iswhich may be properly reinforced as shown. 0n the upper end of the arm,I provide a hole adapted to receive a bolt 80, which is turned down andthreaded in the shaft 60. Also on the upper end of the support, there isa. slot 8| designed to receive the flange 63 of the box H,'when the boxis supported by the bolt 80. It is to be understood that the, bolt 80turns in the arm #9 and that the flange t3 slides through the slot 8|,thus permitting the boom to be swung in a vertical plane. My inventionalso provides means for clamping the boom in any vertical position andas shown comprises a screw threaded bolt 32 mounted in the upper end ofthe support and adapted to engage and press the flange 63 in the slotat. A short rod 83 may be used for turning the bolt 82.

In operation, the rod 3 is extended or retracted by turning the crank70. As the crank is turned, the piston 58 together with the weight as ismoved in the barrel F. This in turn, forces the liquid between thepistons 58 and id to move in response to. the movement of the piston i8and the piston 55 is correspondingly moved. As mentioned before, thebarrel A is of less diameter i 9,188,808 n, which is bored and equippedwith bushin place and held stationary.

. sign of the rod B.

ranged so that said -tension or retraction. The whole assembly is acompact, light. durable piece of equipment that 10 requires little or nomaintenance and performs silently.

Altho gh I have shown a-detailed preferred form of my invention, I amaware that certain,

parts may be modified and refined without de- 15 parting from theinvention. I, therefore, intend this disclosure to coverall suchalterations that come within the essence of theinvention-asexpressed inthe appended claims.

' I claim: i Y m 1. In an extensible boom having a support in.-termediate its ends: a barrel; a rod slidably mounted in said barrel; apiston connected to saidrod; a second barrel having an interconnectingpassage to said first mentioned barrel; a piston in said second barrel;a weight attached to said piston; liquid connecting said pistons; andmeans for moving said piston and weight in said second barrel to movethe piston and rod in said first mentioned barrel in an oppositedirection.

2. In an extensible boom having. a support intermediate its ends: a pairof interconnecting barrels; a piston in each of said barrels; a rodconnected to one of said pistons and a weight connected to the other ofsaid pistons; liquid connecting the pistons; and means for moving thepiston and weight in one barrel to move the piston and rod in the otherbarrel in an opposite direcetion.

3. Inan extensible boom having'a support intermediate its ends: a pairof barrels having an interconnecting passage at one end thereof; apiston in each of said barrels; a rod connected to one of said pistonsand a weight connected to the other of said pistons; liquid connectingthe pistons; and means for moving the piston and weightin one of saidbarrels in one direction to move the piston and rod in the other barrelin the opposite direction.

4. An extensible boom comprising: a pair of go interconnecting barrels;means for supporting said boom intermediate its ends; a piston in eachof said barrels; liquid connecting saidpistons; a rod connected to oneof said pistons; a weight and a rack bar connected to the other of said55 pistons; a pinion gear mounted in said supporting means and adaptedto mesh with said rack bar; and means for-rotating said pinion gear tomove said pistons, said barrels being arranged so that the movements ofsaid pistons and their e0 associated parts are in opposite directions.

5. An extensible boom comprising: a first barrel and a second barrelhaving an interconnecting passage therebetween; a piston in said firstbarrel and a rod connected to said piston; a piston in said secondbarrel: liquid connecting the two pistons; a weight and a rack barattached to the piston in said second barrel; the piston in saidsecondbarrelbeing connected to the weight and rack bar to allow freetransverse movement be- 0- tween the piston, the weight, and the rackbar; and means for moving said rack bar longitudinally to move saidpistons, said barrels being arpistons move in opposite directions. is

a. In an extensible boom having a support intermediate its ends: a pairof interconnected barrels; a piston in each of said barrels; liquidbetween said pistons; a rod attached to one of said pistons; a weightassociated with the other piston; means for moving the piston and weightto move the piston and rod in an opposite direction.

7. In an extensible boom having a support intermediate its ends: a pairof interconnected barrels, one of said barrels being of larger diameterand shorter length than the other; a piston in each of said barrels;liquid connecting the pistons; a rod connected to the piston in thesmaller barrel; a weight associated with the piston in the largerbarrel; and means for moving the piston and the weight in the largerbarrel to move the piston and the rod in the smaller barrel in anopposite direction.

8. In an extensible boom having a support intermediate its ends: a pairof interconnected barrels; a piston in each of said barrels; liquidconnecting the pistons; a rod connected to one of said pistons and aweight associated with the other of said pistons; and means for movingsaid piston with its weight in one direction to counterbalance themovement 01 the piston and rod in an opposite direction.

9. In a counter-balanced extensible boom having a pivotal support: apair of inter-connected barrels; a piston in each of said barrels;liquid connecting said pistons; a rod connected to one of said pistonsand a weight associated with the other of said pistons; and means formoving said piston with its weight in one direction to maintain thebalance of said boom and to move the piston and rod in an oppositedirection.

ARTHUR GEORGE wman'r.

